In Philadelphia, Mayor Michael Nutter faces a colorful longshot challenge in Tuesday's Democratic primary from T. Milton Street, the brother of his predecessor and longtime political rival, who carries the support of several unions disenchanted with the incumbent.
Nutter, 53, shares the ballot with Street, 72, a former state legislator and hot dog vendor who recently completed a federal sentence for failing to file taxes, and hopes to mobilize ex-offenders as part of his campaign. Street is the older brother of Nutter's predecessor, two-term mayor John F. Street, who recently switched his registration to independent and may be considering a run for a third term in November.
For now, the race is between Nutter and Milton Street in a city where Democrats outnumber Republicans by a margin of nearly 6-1. Polls opened at 7 a.m. in what is expected to be a low-turnout election.
Two lesser-known Republicans square off in the Republican primary: Karen Brown, a former schoolteacher who up until recently was a Democrat, and John Featherman, a real estate agent. Philadelphia hasn't had a Republican mayor since 1952.
There are many other races up for nomination, if you are registered with a party in Pennsylvania. All 17 city council seats in Philadelphia have primaries. Voters will also choose candidates for city commissioners and sheriff.
Statewide, there is an open seat on the Superior Court, as well as the Commonwealth Court, and there are a number of local races outside Philadelphia - including county commissioners, district attorneys, and school board members.
Polling places across the state of Pennsylvania opened at 7:00 a.m. and close at 8:00 p.m.
You can find results for all the races as they come in at 6abc.com.
The Associated Press contributed to this report.